Question

What changes occur in the human eye when it goes from looking at a brightly lit nearby book to viewing a dark, distant scene?

Answer 1

Mainly, two changes occur in the human eye when the eye goes from looking at a brightly lit nearby book to viewing a dark, distant scene:

a) Visual accommodation: The radius of curvature of eye lens becomes more such that the light rays from distant objects still get focussed on the retina only.

b) When we are looking at bright book, our pupil size is small. Now when we view a dark scene, very small amount of light enters due to small pupil size. After some time, our pupil expands which allows more amount of light to enter and we are able to view the dark scene properly.